Vibrio cholerae lives in water and gets the genes to produce a toxin from a virus (phage conversion). The toxin kills the intestinal epithelial cells in the human host resulting in massive diarrhea. Untreated cholera has about a 50% mortality rate. How does killing humans help the bacteria?

because the diarrhea helps the bacteria to spread

Explanation:

Based on the scenario being described within the question it can be said that killing humans helps the bacteria because the diarrhea helps the bacteria to spread. This is because cholera easily spreads in water, killing the intestinal epithelial cells in the human host allows the escrement to become more water, thus allowing the virus to spread more easily.

this is a good question! i'll do some research and come back when i have the answer!